[Arpe]

I don't want to taint this poll, but I have read and re-read the owners manual on this, and cannot think of one good reason to ever use this.

So if you use it, please provide a description and tell me why it isn't a White Balance button which I would use ALL OF THE TIME.

I use the AF button ALL THE TIME, and nver change the WB from auto. The shutter button half press does not AF for me. This is great for sports shooting as you can keep your finger on the shutter button ready to go without worrying about refocussing on an undesired object.

[laissezfaire]

these were all good answers. I'm going to try it out, but I don't shoot sports so I'm still not sure if I need it. I still would prefer a WB button since it's nice to have a RAW file that looks the way it should to start with.

[Marc Sabatella]

these were all good answers. I'm going to try it out, but I don't shoot sports so I'm still not sure if I need it. I still would prefer a WB button since it's nice to have a RAW file that looks the way it should to start with.

My take is this:

WB is something you need to change when you change from one lighting environment to another. How often are we talking about - maybe a few times a day? Especially given that auto WB isn't *that* bad as a starting point for RAW processing, except in tungsten light, so really, the only time you really "need" to change WB is entering or leaving a tungsten-lit environment. And even then, "need" is a strong word, because we *are* talking about just a starting point for processing, not an immutable quality of the picture.

Whereas focus is something you generally do not a few times a *day*, but many times per *minute*, usually. It's something you deal with with second-by-second, on every shot you take, and it *cannot* be adjusted after the fact. It is imperative to get it the best you can when shooting, and the more control you have, and the more quickly you can exercise that control, the better. No way could I accept a camera that was not able to disassociate focus from shutter press - it would be all but unusable. Although, FWIW, I personally use a button to *cancel* AF rather than to perform it. Still, that's an absolutely indispensable feature. And not just for sports. Anything where you might take several shots in a row of the same scene and are concerned about having the focus consistent. Portraits, concerts, candids, landscapes, you name it. It's silly to have the camera refocus after every shot when there is no need - all that does is give the camera chance to choose a different focus point next time, after you've carefully made sure you got it right the first time.

So between WB and AF, there is no question in my mind which is more important to have as a dedicated button. Not even close.

[PDL]

these were all good answers. I'm going to try it out, but I don't shoot sports so I'm still not sure if I need it. I still would prefer a WB button since it's nice to have a RAW file that looks the way it should to start with.

I do not shoot sports as a general subject. I have shot sports (Cricket in NZ and Baseball a few months ago) and I would not like to have the d*mn machine hunting for something to lock onto.

Don't go thinking that this is all about Sports and use that as a reason to leave control up to the machine. This is all about YOU and control. If YOU let the machine be the one making the decisions - stop complaining.

I disagree with Marc however, I do not want the camera trying to focus unless I tell it to. If a shot is lost due to focus issues - they are MINE - not the camera's. Therefore I have de-coupled AF from the shutter button on all cameras where it is available. (All my Pentax DSLR's but not my new C*non P&S - it will not let me in a consistant fashion - I bought a C*non because it has a viewfinder - that works - no current Pentax P&S has a viewfinder).

The whole idea from my perspective is to have the ability to control the fundamental elements of taking pictures. If you let the machine make the decsions for you - then YOUR creativity is lessened. Don't be a clone - branch out and find what works for you, defeat the defaults - it just feels better.

Edit: For those of you who say you do not have one - Look in the threads I posted earlier. The *istDx series of cameras will let you use the OK button after the shutter button is de-coupled. It works, it is just not all that fancy - the creative control you gain more than outweighs any OK functionality. It is in the manual also - but you have to go look it up, buried in the custom control menus. If you have K series camera it should be there also.

The Elitist - formerly known as PDL

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Last edited by PDL; 12-15-2008 at 12:05 AM. Reason: AF via OK/AF on non K10/20 cameras

[Syb]

It is a usual setting for pros. The following link explains all. I used this a lot in Canon system....


Canon Digital Learning Center - Back-Button Auto Focus Explained

Thanks. After reading the line quoted below, I'll think I'll have to give it a try at least....

With back-button AF, this becomes a nearly foolproof feature.

[WMBP]

I generally shoot in M mode and control every other option manually, but for a long time, I was content to use the camera's default with respect to focus, that is, to let the camera focus automatically when I pressed the shutter half way. It seemed like a good idea for a long time. In fact, it seemed almost necessary. I used to shoot full-manual with my film SLRs, but I don't think I ever had a film SLR that supported auto-focus, so I was focusing manually, as well. When I got into digital photography around 2000, it felt like a luxury to let the camera focus for me. Actually, during those several years with compact digital cameras, although I had taken care to buy cameras that supported full-manual control of exposure (Olympus Camedia C3000, and several Canon PowerShot S-series superzooms), I ended up letting the cameras adjust exposure automatically as well as focus, because full-manual control of exposure was such a pain. I didn't miss manual focus during that time but I did miss manual control of exposure, and that was one of the main reasons I moved up to a digital SLR.

And once I did that, I eventually started to feel that controlling everything else manually but letting the camera auto-focus didn't make lots of sense. More importantly, shutter-activated autofocus did occasionally cause me problems. I shoot a lot in low light, and occasionally the camera would miss an important shot because it failed to focus when I pressed the shutter. And I do fairly regularly compose shots in which the focal point is off-center, and those shots sometimes presented a challenge: the center of focus might be on the left side of the shot, but the center of exposure might be somewhere else. Actually, that happens a lot and as a result I already use the AE-lock button pretty routinely.

So earlier this year, I decided to delink auto-focus from the shutter button and start using the AF button at my own discretion. This was a natural step for me. Even so, it took me several hundred shots to get used to it. I'm an event photographer, and generally I'm shooting lots of shots pretty quickly. So no matter what method I use, focusing HAS to be reflexive, something that can be done (or skipped) without much thought. Anyway, I got it down and now I really like it. I can't imagine going back.

I do agree entirely with those who wish the K10D/K20D grip had an autofocus button. It's crazy that it doesn't. It also bothers me that the AE-lock button is in a quite different spot on the grip from where it is on the body of the camera. I like using the grip. But I do not like the way the buttons are placed when I turn the camera sideways.

I hasten to add that this is a purely practical decision for me, and not a matter of personal virtue! I experimented quite a bit in 2008 with the K10D/K20D's hyper-manual mode - where I put the camera in P, and then control exposure manually by setting either shutter OR aperture and if necessary adjusting the meter using AE+/-. At first, it seemed like a great idea and if you search, you'll find some enthusiastic posts about it from me in this forum. Eventually, I decided that, for me anyway, switching back to M was easier. So I did. My point is that photography isn't gymnastics and you get no points for difficulty. If you can take pictures you're happy with the camera in green (fully automatic) mode, I'm not sure why you would want to try anything else.

I'm frankly surprised at the results of this poll. I am quite sure that the large majority of ordinary folks using digital SLRs have autofocus tied to the shutter. Attaching auto-focus to the shutter button is a nice option and probably a good idea for a lot of photographers, especially casual photographers.

Will

[Marc Sabatella]

I disagree with Marc however, I do not want the camera trying to focus unless I tell it to. If a shot is lost due to focus issues - they are MINE - not the camera's. Therefore I have de-coupled AF from the shutter button on all cameras where it is available. (All my Pentax DSLR's but not my new C*non P&S - it will not let me in a consistant fashion - I bought a C*non because it has a viewfinder - that works - no current Pentax P&S has a viewfinder).

Note I don't disagree with this at all. I do agree it is imperative to have the ability to decouple AF from the shutter; indeed, that was my point. I just happen to be lazy & forgetful enough to prefer the mode in which the default is to perform AF with shutter half-press, so I can perform the disassociation when I choose, by hitting the button to cancel AF. But It amounts to the same thing in practice - *I* am in control of when the camera focuses. One action causes the camera to focus, another causes it not to. Only real difference is that we are reversing which action (pressing button, not pressing button) does which.

Edit: For those of you who say you do not have one - Look in the threads I posted earlier. The *istDx series of cameras will let you use the OK button after the shutter button is de-coupled. It works, it is just not all that fancy - the creative control you gain more than outweighs any OK functionality.
It is in the manual also - but you have to go look it up, buried in the custom control menus. If you have K series camera it should be there also.

Yes, I started doing this on my DS, and have continued doing so on my K200D. Although there are a couple of other useful things one could assign the OK button to do - display ISO, return focus selection to center point when using the user-select mode, etc - none in my mind are more important than this.

Of course, on a camera as otherwise customizable as the K20D, I'd completely sympathize with the notion that someone might for whatever reason decide to give up control over focus in favor of faster access to WB. No way would *I* make that choice, but I'm assuming it would have been possible to have provided this option in firmware, had it occurred to anyone at Pentax that someone might want to do this.

[farfisa]

I actually prefer using the AF button to autofocus and disable the half-press focusing, but I switched just to make it easier for others to use my camera.

Now I have AF set to cancel, and that works pretty well too.

I would absolutely love it if it was a true switch to MF, making everything quick-shift (in a way).

[laissezfaire]

I found a serious flaw with the AF button used exclusively with the the half-press shutter focus disabled.... it took a whole 2 minutes to observe this.

**** Shake reduction doesn't work unless you wait for the visual cue (on the right side of the viewfiinder) upon a half press, then fully press the shutter. I did a search and this is actually noted by others but not really addressed by AF button advocates. ***********

So in a condition requiring SR, if you don't half press and visually see the SR icon, then you will be shooting w/o SR! I tried it and confirmed this flaw. (and also confirmed the benefit of SR)

On the other hand, if you leave AF on the shutter button, then the half press gets you 1) SR activation, 2) auto focus lock, 3) small confirmatory beep emitted, then you press fully.

To address situations in which AF is not required, it seems to me that it's best to use the AF button to DISABLE shutter AF.

[KungPOW]

I found a serious flaw with the AF button used exclusively with the the half-press shutter focus disabled.... it took a whole 2 minutes to observe this.

**** Shake reduction doesn't work unless you wait for the visual cue (on the right side of the viewfiinder) upon a half press, then fully press the shutter. I did a search and this is actually noted by others but not really addressed by AF button advocates. ***********

So in a condition requiring SR, if you don't half press and visually see the SR icon, then you will be shooting w/o SR! I tried it and confirmed this flaw. (and also confirmed the benefit of SR)

On the other hand, if you leave AF on the shutter button, then the half press gets you 1) SR activation, 2) auto focus lock, 3) small confirmatory beep emitted, then you press fully.

To address situations in which AF is not required, it seems to me that it's best to use the AF button to DISABLE shutter AF.

Even if you use the shutter release to activate autofocus, you still need to wait a sec for the camera to activate SR.

The AF button on the back will only activate autofocus. The shutter still activates SR. I don't see this as a bug or a defect, it is just the seperation of the two functions.

But the neat thing is that you have a choice of how you want to set up your camera.

[PDL]

I found a serious flaw with the AF button used exclusively with the the half-press shutter focus disabled.... it took a whole 2 minutes to observe this.

**** Shake reduction doesn't work unless you wait for the visual cue (on the right side of the viewfiinder) upon a half press, then fully press the shutter. I did a search and this is actually noted by others but not really addressed by AF button advocates. ***********

So in a condition requiring SR, if you don't half press and visually see the SR icon, then you will be shooting w/o SR! I tried it and confirmed this flaw. (and also confirmed the benefit of SR)

On the other hand, if you leave AF on the shutter button, then the half press gets you 1) SR activation, 2) auto focus lock, 3) small confirmatory beep emitted, then you press fully.

To address situations in which AF is not required, it seems to me that it's best to use the AF button to DISABLE shutter AF.

You are missing the point. You still have to push the shutter button to activate the electronics of the camera no matter what method of AF you are using. SR is activated by half pressing the regardless of AF method.

That said, do this with AF attached to the shutter button.
Go to a baseball game, manually get "close" to being in focus on third base - press the shutter button to turn on the electronics - press the AF button and set the exposure - using what ever method you want. Remember - you are anticipating a play at third base - not 6 feet behind third base where the third baseman is. Now wait for the play - and you take your finger off the shutter button - everything is locked for 10 seconds (remember, you understand baseball here). When the play begins - you press the shutter button (keeping both eyes open to follow the timeing of the action) - as the play progresses you press the shutter and the camera takes the picture.

Do this with AF coupled to the shutter button and when you press the shutter - the camera goes a hunting - will THE CAMERA pick the base, the player or the N*kon sign in left field? Only the camera knows - you are just the thing that pushes the button - you, in my opinion, are not in control.

The same sort of scenario can occur in landscapes, portraits, weddings - just about any type of photography. If you are shooting in situations where you need SR and high ISO - then you need to rethink your dependency on SR "having" to be there.

Edit: When I first used my Pentax DSLR during my son's HS graduation, I did not know how or even that you could de-couple AF from the shutter button. (I did not know how to use my manual 300mm either, but that is a different story) So I am taking image of my son as he walks out of the stadium (insert theme music here). I fire off three or four shots and the camera tracks and focus's nicely - then IT chooses the back of the head of the guy in front of me - focuses and shoots. Oh nice - clear shots of a bald spot (even worse than mine at the time) just what I wanted. (No SR on a *istDs either and a Tokina 28-70mm at the max) Learn to take control - you will never go back.

The Elitist - formerly known as PDL

[GeneV]

I found a serious flaw with the AF button used exclusively with the the half-press shutter focus disabled.... it took a whole 2 minutes to observe this.

**** Shake reduction doesn't work unless you wait for the visual cue (on the right side of the viewfiinder) upon a half press, then fully press the shutter. I did a search and this is actually noted by others but not really addressed by AF button advocates. ***********

So in a condition requiring SR, if you don't half press and visually see the SR icon, then you will be shooting w/o SR! I tried it and confirmed this flaw. (and also confirmed the benefit of SR)

On the other hand, if you leave AF on the shutter button, then the half press gets you 1) SR activation, 2) auto focus lock, 3) small confirmatory beep emitted, then you press fully.

To address situations in which AF is not required, it seems to me that it's best to use the AF button to DISABLE shutter AF.

I shot exclusively with the half-press focus disabled until I realized this. Partly, it was because I jumped from manual focus 35mm to the K10d and could not let go of the focus control.

I am now retraining a bit to use the half-press in situations where camera shake is an issue. Also, if you pick up the camera with a quick grab shot, (or a helpful passer by takes a shot of me) the camera will let you take an out of focus shot with the half-press disabled. I like that for speed when I have gotten it together to use the AF button, but I've had a few blown that way, too. Re-learning the half-press also helps me when, in the opposite situation described by another poster, someone hands me their camera for a shot. I would find myself hunting with my thumb for their AF button and hitting something else, like exposure adjustment.

So now, I keep the half-press, but still frequently use the AF button to freeze the focus point.

Since I shoot only PEF, I can't see the need for a WB button. PS does a better job at WB than the camera anyway.

[Ratmagiclady]

So... Hope no one minds if I revive this conversation after having had my k20d in hand a few days... I'm still playing with settings... and the way I'm a creature of habit with these things, this is a biggie.

My initial idea of what to do was to configure so that a half-press of the shutter would be metering/ae hold, and use the AE-L button for AF-on.

Apart from that I can't seem to make a half-press do that, and I'm not wild about where the AE-L button is for purposes of reaching up there every time I want to grab focus, (Though maybe I could make this happen by linking ae-l to af and then disabling af-at-the-half-press?) I've got another promising idea that I'm trying:

This is basically, stock settings with the AF button set to 'disable af.'

See, I've got a long-ingrained habit of riding the shutter-half-press to keep the meter live on my old Canons, and to grab focus, I can just blip that and focus stays where I put it till release. This seems pretty compatible with using the AE-L when I want to just do what I've done a lot with my P&S camera, which is usually to point at something that'll tell a meter to do what I want and hold it there. (On the P&S, this was much less of a pain than trying to set things manually)

So I think I have a scheme that may work nice: I think if there was a button right under thumb for AF, it might be a little different, but this seems promising.

[kjfaust]

i want to use the AF button but since I only have a K100d S I have to use the OK button
and the position of the OK button is a bit awkward to press for me as oppose to the position of the AF button in the k10d or k20d

[alohadave]

Edit: When I first used my Pentax DSLR during my son's HS graduation, I did not know how or even that you could de-couple AF from the shutter button. (I did not know how to use my manual 300mm either, but that is a different story) So I am taking image of my son as he walks out of the stadium (insert theme music here). I fire off three or four shots and the camera tracks and focus's nicely - then IT chooses the back of the head of the guy in front of me - focuses and shoots. Oh nice - clear shots of a bald spot (even worse than mine at the time) just what I wanted. (No SR on a *istDs either and a Tokina 28-70mm at the max) Learn to take control - you will never go back.

The Elitist - formerly known as PDL

This is why I disabled all but the center AF point. I'd rather not fight the camera for control of what is selected to be in focus. Most of what I shoot is not going to be affected by focus errors caused by recomposing, so getting focus then recomposing works best for me.